The invention relates to an assembly method for the rapid erecting of steam generators.
Steam generators or large-scale boilers of this type are used primarily in power plants heated with fossil fuels in which the heat, released in the combustion chamber of the steam generator through the burning of fuels, is absorbed by a working medium circulating in the steam generator and the heat energy is, for example, imparted to a turbine for power generation. In that regard, the large steam generators, which are often called single-pass boilers, are equipped with vertically arranged gas passes, in which the combustion takes place in the lower region and which are delimited by tube or boiler walls, whereby the tube or boiler walls are formed by inclined or vertically arranged tubes that are connected with each other. Arranged in the upper part of the gas pass are internal components such as economizers, reheaters, superheaters and other heating surfaces. On its outside, the boiler wall is provided with buckstays and header wall boxes, which include headers arranged on header cross-ties. Connected at the lower end of the boiler wall is a boiler hopper, which hangs above a so-called boiler base (usually the 0 m (zero meter) platform). The complete boiler to which the mentioned elements belong is arranged suspended in a boiler steel structure. The boiler steel structure rests upon a foundation that delimits the boiler base and exhibits several boiler columns, which are braced by means of crossbeams and steel structure diagonal braces and which bear a boiler top grid. The boiler top grid bears the boiler, which is provided at the top, underneath the boiler top grid, with a boiler roof.
For rapidly erecting large steam generators of this type, DE 100 14 758 C2 suggests a method that makes it possible to simultaneously construct the upper part of the boiler wall and the internal components that are to be provided there. For that purpose, the boiler top grid is divided into an outer top grid section and an inner top grid section. The boiler steel structure is first erected with the outer top grid section. The latter is configured in such a way that it provides access from the top to the volume enclosed by the boiler steel structure. By means of a crane, parts for the construction of the boiler wall, the upper boiler wall in particular, can thus be lifted in from above through an opening left in the outer top grid section. This makes it possible to assemble the upper boiler wall by means of a crane of a suitable size. Simultaneously, the inner top grid section of the boiler top grid can be constructed on the boiler base or just above same. It is held, for example, by means of tension cables having lifting systems that are anchored in the boiler steel structure, e.g., at the outer top grid section of the boiler top grid. The required internal components are now constructed underneath the inner top grid section of the boiler top grid, whereby the inner top grid section of the boiler top grid can accordingly be lifted gradually. The assembly of the upper boiler wall and the assembly of the internal components thus take place parallel in time. Because both of the assembly operations are each very time-intensive, a great deal of construction time can be saved by means of parallel assembly. Once both the upper boiler wall and the internal components have been completed, the internal components including the inner top grid section of the boiler top grid can be hoisted and fastened and connected at their installation location.
This method has been well-proven for erecting large steam generators. There is now a need, particularly in view of the recent exorbitant increases in steel prices, to further optimize and simplify this well-proven method, and to minimize the use of steel, particularly for auxiliary constructions.
It is thus the task of the invention to create a method which, along with a simple and rational construction, also allows the construction especially of large steam generators in a way that is cost-effective in terms of steel, and which is already simpler to undertake in the engineering and thus faster and more cost-effective.